Asuka Arimoto
Marine Biological Laboratory, Graduate School of Integrated Sciences for Life, Hiroshima University, 2445 Mukaishima, Onomichi, Hiroshima, Japan
Caulerpa lentillifera is a multinucleated unicellular organism showing complex morphological structures analogous to land plants. The morphological differences among structures in a Caulerpa cell seem to be determined by the preferentially localization of biological molecules such as RNAs or proteins. In our previous study, the comparison of transcriptomic profiles between two different structures of C. lentillifera, fronds and stolons, showed that over 1,000 genes were expressed preferentially in each structure.
Although there is limited knowledge of protein localization in a Caulerpa cell, our transcriptome analysis indicated that gene ontology terms associated with protein translation are enriched in the stolons. The results suggest a hypothesis that proteins in a Caulerpa cell are mainly translated in the stolon, then some of the translated proteins are transferred to other structures such as fronds. To investigate the hypothesis, we extracted toral proteins from C. lentillifera and identified the proteomic profiles using shotgun mass spectrometry. Unexpectedly, the results did not clearly support the hypothesis, however, preferentially localization patterns of the proteomic profiles were different from the patterns of the corresponding transcripts. In addition, some of ubiquitous expressed transcripts were preferentially localized as proteins in the fronds or stolons. These results suggest that the protein localization in C. lentillifera is regulated by the different mechanisms of RNA localization.